Fuel guage question

Joined
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I bought a second ST and the fuel gauge is acting oddly. It goes down the three bars just fine but then "sticks" there until it drops to one flashing bar reading 30-40 miles left. It never displays two bars remaining. Has anyone else had this issue? Is there a fix or a likely cause?

Bob
 
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Mine does the same thing....it is most likely the fuel level sensor, inside the gas tank. Sometimes, the arm which has the float on it gets bent, ( it is not very stout), and it gets stuck at 3 bars, until the thermistor in the bottom tank goes dry, and shows it as almost empty. I think some folks have cleaned off the contacts, or bent the arm, or just replaced the sender. It bothered me for a while, then I just started filling up earlier.
 

Mellow

Joe
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From STwiki:
Lower tank fuel sensor:

Full sensor, in can: Panasonic ERTLG12N7 (unverified). The same sensor is believed to be used in the fuel sender assembly found in many Toyotas, particularly the 1985 Corolla. Source: http://www.southbayriders.com/forums/threads/135817
Thermistor only: Ametherm NT05 15291
 

docw1

Bill Rankin
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This happened to me last fall and kept it up for the rest of the year. Now, after winter storage with SeaFoam in the tank, it has started to work normally again. Don't know if it's cause and effect, but it is what it is.
 
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From what I could find out by reading, and reading between the lines: If the thermistor is bad, the fuel gauge won't work at all, just flashes the one bar. When the upper tank gets low, the fuel gauge should show one bar- the next indication is the flashing bar, indicating one gallon or so left.

Apparently, the "arm" on the fuel level sensor is very fragile-even a hard stream of gas is enough to bend it, causing it to read high. SO, it reads 3 bars, although the upper tank is empty, until the (dry) thermistor shuts the display off, and flashes.

The sensor is accessed under the tank, and according to one source, can be removed with the tank on, but it's tough. Not an overly expensive part, and at least one poster cured his bad sensor by cleaning the contacts with a pencil eraser. Probably a good time to replace the big tube going from tank to tank anyway.
 

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Joe
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The sensor is accessed under the tank,
Nope, it's inside the tank attached to the assembly the fuel pump is attached to. You can see it here with the entire assembly out of the lower tank:
 
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Nope, it's inside the tank attached to the assembly the fuel pump is attached to. You can see it here with the entire assembly out of the lower tank:
I was referring to the fuel level sensor in the top tank....shoulda been more specific.
 

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Joe
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I was referring to the fuel level sensor in the top tank....shoulda been more specific.
Ah, okay yes you can get to it with the tank on but the top tank is pretty easy to get off so why not do that.

It's definitely easier to replace/fix the upper sending unit than the thermistor.
 
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ajax.ontario.canada.
Min
I bought a second ST and the fuel gauge is acting oddly. It goes down the three bars just fine but then "sticks" there until it drops to one flashing bar reading 30-40 miles left. It never displays two bars remaining. Has anyone else had this issue? Is there a fix or a likely cause?

Bob
e mine does just that. Exactly that. What fixed it? E mail me please. Spiv@rogers.com
 
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I bought a second ST and the fuel gauge is acting oddly. It goes down the three bars just fine but then "sticks" there until it drops to one flashing bar reading 30-40 miles left. It never displays two bars remaining. Has anyone else had this issue? Is there a fix or a likely cause?

Bob
 
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Messages
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ajax.ontario.canada.
The fuel sensor assembly in the upper tank. Replaced that and all is good.
Thank you so very much for your reply. Like I said mine does exactly that. After replacing the thermistor I knew it still was not right. Seemed to stick on three bars, Then next flashing reserve! I gave up and just reset my odometer all the time. When you said stuck on three bars it confirmed you had the same issue. Once you said once the thermistor sees air it starts the countdown,I knew mine was stuck on three ,good to hear replacing the gauge fixed it I am confident enough to order a gauge and hopefully fix the problem. If this is the case I surmise that the float is bent and can never go lower than three. Someone surgestEd filling it too vigorously can bend the float, The answer? Thanks so much it’s been a while chasing this issue.
 
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From what I could find out by reading, and reading between the lines: If the thermistor is bad, the fuel gauge won't work at all, just flashes the one bar. When the upper tank gets low, the fuel gauge should show one bar- the next indication is the flashing bar, indicating one gallon or so left.

Apparently, the "arm" on the fuel level sensor is very fragile-even a hard stream of gas is enough to bend it, causing it to read high. SO, it reads 3 bars, although the upper tank is empty, until the (dry) thermistor shuts the display off, and flashes.

The sensor is accessed under the tank, and according to one source, can be removed with the tank on, but it's tough. Not an overly expensive part, and at least one poster cured his bad sensor by cleaning the contacts with a pencil eraser. Probably a good time to replace the big tube going from tank to tank anyway.
You have made my day. I have been chasing this iss for a second year, replaced the thermistor. now your storey considers the float bent never going below two makes total sence to me, Took a while to connect the dots ,thanks
 
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You have made my day. I have been chasing this iss for a second year, replaced the thermistor. now your storey considers the float bent never going below two makes total sence to me, Took a while to connect the dots ,thanks
I have since taken my tank off, and took the fuel sensor out, cleaned it using an abrasive eraser, and it works just fine now. After removing the sensor, I can tell you that it is not NEARLY so fragile as I was led to believe. The inaccuracy seems to be due to crap building up on the contacts on the sensor, which come off quite easily. I have read that it is the ethanol in the gas that corrodes/gunks up the contacts, but I think it is just the overall level of crud in modern fuel.
NOTE: if you plan to remove the sensor, get a new O-Ring for it.
 
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I have since taken my tank off, and took the fuel sensor out, cleaned it using an abrasive eraser, and it works just fine now. After removing the sensor, I can tell you that it is not NEARLY so fragile as I was led to believe. The inaccuracy seems to be due to crap building up on the contacts on the sensor, which come off quite easily. I have read that it is the ethanol in the gas that corrodes/gunks up the contacts, but I think it is just the overall level of crud in modern fuel.
NOTE: if you plan to remove the sensor, get a new O-Ring for it.
I Realy want this issue gone, All the stuff I have gone through so far is just too much trouble! Replacing the defective fuel level sensor will be a joy just to get away from the problem. It’s winter here in Canada right now, draining the tank is such a pain ,I will run her dry then pull the tank off,replace the fuel sender,new gasket then pray a lot. I have to mention the most idiotic thing I have ever done and got away with it. Replaced the thermistor,went to the gas station and filled her up to the brim. Noticed the big puddle on the floor was Geting bigger and bigger. Yes the gasket around the fuel pump wasn’t seated and gas was pouring all over the catalytic mufflers and sizzling, I pushed her off to the road and it didn’t burn but stoped only when all that great new gas was on the floor. I prayed a lot! For a while I filled a gas can and refueled it cold in my garage. After installing a new gasket ,I eventualy started trusting the new gasket and watching the trip meter. Hopefully I can check this off my list of concerns and be normal once more.
 
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I Realy want this issue gone, All the stuff I have gone through so far is just too much trouble! Replacing the defective fuel level sensor will be a joy just to get away from the problem. It’s winter here in Canada right now, draining the tank is such a pain ,I will run her dry then pull the tank off,replace the fuel sender,new gasket then pray a lot. I have to mention the most idiotic thing I have ever done and got away with it. Replaced the thermistor,went to the gas station and filled her up to the brim. Noticed the big puddle on the floor was Geting bigger and bigger. Yes the gasket around the fuel pump wasn’t seated and gas was pouring all over the catalytic mufflers and sizzling, I pushed her off to the road and it didn’t burn but stoped only when all that great new gas was on the floor. I prayed a lot! For a while I filled a gas can and refueled it cold in my garage. After installing a new gasket ,I eventualy started trusting the new gasket and watching the trip meter. Hopefully I can check this off my list of concerns and be normal once more.
This may also help: https://www.st-owners.com/forums/threads/how-i-fixed-my-flashing-fuel-guage-issue.170324/
 
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